The present invention relates to a method and apparatus for producing specifically shaped products and, more particularly, to the production of food products within configurated die cavities such that the food products have specific shapes and weights.
U.S. Pat. Nos. 4,212,609 and 4,957,425 disclose methods and machines for producing configurated and specified weight products in die cavities of a rotary die roll, each of the die cavities being defined by a configurated side wall and a porous bottom wall. The machines disclosed in each of these patents work on similar principles such that during each revolution of the die roll a batch of product is forced into each cavity as the cavities pass beneath a feed hopper. Upon continued rotation of the die roll, the bottom walls of the cavity are moved outwardly so as to force the configurated products from the die cavities. Simultaneously with the outward movement of the cavity bottom wall, air is directed through the porous bottom walls so that the configurated product is forced off of the wall and onto a conveyor located beneath the die roll.
The die cavities of the rotary die rolls disclosed in each of the above-identified patents are arranged in longitudinal rows circumferentially spaced about the periphery of the die roll. One problem associated with the arrangement of the two feed rolls and the die roll disclosed in each of the above patents is that excessive pressure can build up in the space between the feed rolls and the die roll which causes the product contained therebetween to become excessively worked and hardened. U.S. Pat. No. 4,957,425 discloses a backing knife or seal which occupies approximately one half of the volume of the generally triangular pressure chamber created between the feed rolls and the die roll. However, the size of the backing knife or seal is limited in that it does not and cannot extend too far into the pressure chamber without interfering with the path which the product must take to the die cavities and thereby decreasing the time available for loading the die cavities with a proper amount of product.
Another problem associated with such past machines is associated with their ability to easily enable changeover or maintenance of the die roll. In this regard, disengagement of the feed rolls from the die roll and removal of the die roll from the machine to allow it to be replaced with another die roll which, for example, forms differently shaped products is a difficult and involved procedure.
The above-mentioned patents further do not provide a cost efficient manner of replacing the shearing element of the front shearing knife. The front shearing knives disclosed in each of the above patents are one piece units which must be replaced in their entirety if, for example, the shearing surface is damaged by solid particulates, such as bone pieces, in the product. Frequent replacement of the entire front shearing knife is cost inefficient both in terms of the machine down time involved as well as the expense of the shearing knife itself.
While the above patents also disclose the use of tapered longitudinal recesses in the feed rolls to aid in feeding product into the pressure chamber and against the die roll, recesses of each feed roll are in line with one another and directly opposed to one another as they meet at the point where product is fed into the pressure chamber above the die roll. The problem with having such aligned, opposed recesses in the feed rolls is that particulates within the product can get caught in the spaces between the recesses and get crushed during the feeding process. That is, at the points between opposed smooth surfaces of the feed rolls, the spacing between the feed rolls may be much smaller than the particulates in a given food product. Thus, when particulates having dimensions greater than this space get caught therein during the feeding process, they will be crushed as they are forced between the feed rolls. This is undesirable in applications requiring that the particulates, such as nuts, candy, etc., remain intact and uncrushed as the food product, such as cookie dough, is shaped by the machine.
Finally, past forming machines have used motors which maintain constant speed as they drive the die roll as well as the feed rolls. The speed motors are chosen so as to maintain product within the pressure chamber above the die roll and force that product downwardly into the die cavities of the die roll as those cavities move past the pressure chamber. The use of such motors operating at a constant speed while driving the feed rolls, however, can cause the torque on the motors to become too high in certain applications and situations, More specifically, if the feed rolls are suddenly subjected to a large amount of product being deposited into the feed hopper or, for example, higher viscosity product being directed between the feed rolls, the resulting torque on the motor or motors driving the feed rolls will increase and may result in either reducing motor life or in complete motor burn out.